This invention relates generally, as indicated, to a surface thermocouple assembly and method of making same, and more particularly, to certain improvements in thermocouple assemblies especially of the type disclosed in U.S. Pat. No. 4,164,433 and their method of fabrication.
The thermocouple assembly of such patent generally consists of a sheathed thermocouple cable having an angularly disposed sensing end, with the sheath terminating at such sensing end in an open end face substantially parallel to the axis of the adjacent axial portion of the sheath. At the sensing end is an end cavity substantially free of insulating material, with a thermojunction of the thermocouple conductors formed in the cavity and an end closure of weld metal substantially filling the cavity embedding the thermojunction therein. The end closure has an exposed face substantially parallel to the axis of the sheath to provide a contact face adapted for contiguous intimate contact with the work surface whose temperature is to be monitored, and such end closure also provides a short direct heat path between the thermojunction and such work surface.
One drawback to such a thermocouple assembly is that some difficulty may be encountered in filling the end cavity of the sheath with filler metal, making such end closures somewhat costly to fabricate. Moreover, the desired weld integrity of such end closures may be hard to maintain, and the shape of the weld metal end closure could be difficult to control. End closures of the best possible integrity with a more consistent shape make them better suited for weld attachment by the customer to the heated surfaces which are to have their temperatures monitored.